Tuesday, November 23, 2010
First day at SPBB
Good to find a boatbuilding company in which I can have my hands on tools and boats. All people there are quite professional and experienced, and very friendly as well.
Sunday, November 14, 2010
Small Craft Building: Week 6
Monday
This is the final week of our small craft building project. This morning, we started with cleaning up the inside of the dory. Which means to get rid of glue. Then we realized that how much glue we have put on our boat. Kind of mess.
The bulk head is another task for today. Bandsaw and jigsaw were used to cut the shape of the bulk head. In order to make it the right size, plane and sanding were necessary. Before working on the bulk, Chris showed us how to find the exact location for the bulk (as the real dory is little bit different from its plan). First make sure that the boat is level (use level to check at the forward, midship and afterward stations of the boat), then put the midship frame back and make it right angle with bottom. Next step is to put bulk head frame back (make sure it is right angle with bottom.
Afternoon, we were preparing lamina for the quarter knees and Jade was working on the fore deck.
This is the final week of our small craft building project. This morning, we started with cleaning up the inside of the dory. Which means to get rid of glue. Then we realized that how much glue we have put on our boat. Kind of mess.
The bulk head is another task for today. Bandsaw and jigsaw were used to cut the shape of the bulk head. In order to make it the right size, plane and sanding were necessary. Before working on the bulk, Chris showed us how to find the exact location for the bulk (as the real dory is little bit different from its plan). First make sure that the boat is level (use level to check at the forward, midship and afterward stations of the boat), then put the midship frame back and make it right angle with bottom. Next step is to put bulk head frame back (make sure it is right angle with bottom.
Afternoon, we were preparing lamina for the quarter knees and Jade was working on the fore deck.
Monday, November 8, 2010
Small Craft Building: Week 5
Monday
Last week, we set up a goal for today: attach the strake (upper topside) to the boat. It is good that we made it today, although this took us 3 hours extra work (We left the workshop at 7 pm).
The first thing this morning was to plane those two scarfed strake (port and starboard), and sand them. Next is to measure their exact size. We tried several times for the measurement.
Another important step is to make the Box Landing at the forward of the garboard and the strake. This requires good skills. Vaughn explained it to us. But I did not really understand until I started work on it. Well, practice helps a lot to understand. But I made a mistake by beveling the box landing too much. This resulted in a big gap between the strake and the garboard when we tried to put them together. The solution? Fill the gap with lot of glue.
In order to fix the strake, we spread two layers of glue, and then nail it to the garboard. This is not enough. We also use several sticks to keep pushing it against the garboard. This makes the boat looks like a spider rather than a dory. Then we fill the gap between garboard and strake with glue. The process took us lot of time and lot of glue.
It is good that we finished this today. Otherwise, it probably will us the whole week and drag us behind the schedule (as we are not ahead of it, so time really matters). I think we have finished the most difficult parts of building the dory.
Sebastien and Tian also finished the skeg this morning and we also glued them together. Tomorrow we will be able to attach the skeg to the boat. Good jobs, Team Morris.
Last week, we set up a goal for today: attach the strake (upper topside) to the boat. It is good that we made it today, although this took us 3 hours extra work (We left the workshop at 7 pm).
The first thing this morning was to plane those two scarfed strake (port and starboard), and sand them. Next is to measure their exact size. We tried several times for the measurement.
Another important step is to make the Box Landing at the forward of the garboard and the strake. This requires good skills. Vaughn explained it to us. But I did not really understand until I started work on it. Well, practice helps a lot to understand. But I made a mistake by beveling the box landing too much. This resulted in a big gap between the strake and the garboard when we tried to put them together. The solution? Fill the gap with lot of glue.
 |
| Box Landing |
In order to fix the strake, we spread two layers of glue, and then nail it to the garboard. This is not enough. We also use several sticks to keep pushing it against the garboard. This makes the boat looks like a spider rather than a dory. Then we fill the gap between garboard and strake with glue. The process took us lot of time and lot of glue.
 |
| Chris (tutor) spreading glue |
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| Spider-look dory |
It is good that we finished this today. Otherwise, it probably will us the whole week and drag us behind the schedule (as we are not ahead of it, so time really matters). I think we have finished the most difficult parts of building the dory.
Sebastien and Tian also finished the skeg this morning and we also glued them together. Tomorrow we will be able to attach the skeg to the boat. Good jobs, Team Morris.
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| Glued Skegs |
Tuesday
The skeg gave us some problems today. First is that one of those two skegs are not glued properly, so we had to take it apart and re-glue it. Secondly, our skegs are 300mm shorter than it should be. So we had to extend it by scarfing. So we have to wait till tomorrow to put these skegs on.
There is another mistake in the stem cabin. We used the wrong nail (steel nail will go rust easily when it touches salt water. Copper, bronze or stainless nails should be used ) to fix it to the stem and did not use the block between the nail and the stem cabin (this makes it difficult to take the nail out. Fortunately Chris promised to take his tool tomorrow and help us to fix the problem).
The center skeg is also cut. James showed us how to draw the curve of the bottom on a piece of wood. And then we transfer the curve to the wood block and got the center skeg cut.
Chris (tutor) also explained the difference between lamination and sawn. As the boat will face constant waves in the water (which might be very strong and cause lot of shock on the boat),the sawn stem or midship frame is not strong enough for these waves. This is because as sawn stem or midship frame, there will be long grain and short grain areas. Short grain areas are very weak and easy to break. So lamination is better choice as it produces much stronger stem and midship frame. More over, we can learn more from lamination as it. By the way, lamination is also more expensive.
The first boat flipped over today! (see the video)
Team 'Hory Dory" flipped their boat (James is the owner) over in the afternoon. This is really a big step forward, not only for the team but also for all CAT program students. As this is a milestone for our learning process.Congratulations! Team Hory Dory.
Hopefully we can flip our boat at the beginning of next week. I am looking forward lot of sanding work.
Wednesday
This morning, Chris (tutor) came to us before we started our work, and asked us to take 15 minutes to discuss and make a plan for the rest of our small craft building project. The reason for this is that with a clear plan and goals, we can work 10% more efficient. Actually the final plan is almost as the same as we discussed before: skegs and gunnels are for today, and other components are for next week.
Chris (tutor) also talked details about fore deck, bulk head, thwarts and other components. Especially about the fore deck, as it is not included in the plan. It seems a real challenge as there are lot of challenging details. I will write more about the fore deck after we finish it.
Another important technique Chris taught us is how to get nails out of the wood. See the video below:
The skegs are more complicated than I expected. As we extended them yesterday by scarfing, this morning is for shaping skegs to the exact shape. The first thing to do is to draw the curve of the bottom of our boat and transfer the curve to skegs. James showed us a good method to do this. So this is not a problem. Then we plane off glue and sand skegs to make it the right shape. Then, skegs are put through big sander machine to get smooth surface and right thickness.
In order to install the skegs to the boat bottom, we have to fix the location of the skeg. Measured from the center line and draw lines for the skegs. And then we drilled several pilot holes on the bottom, these holes are right position for screws and reference for the skegs. After finished these preparation, spread glue on the skeg and put it on the bottom. Then screw the skegs to bottom to fix them.
After the skegs, it is our turn to work on the gunnels. Lot of cramps are used to hold the gunnel to the strake, screws are used as well. We made screws same common spacing.
It is good that we put skegs and gunnels on today. Tomorrow, we will do the sanding and clean up and we will flip over our boat tomorrow afternoon. One big step forward! Cheers!
The skeg gave us some problems today. First is that one of those two skegs are not glued properly, so we had to take it apart and re-glue it. Secondly, our skegs are 300mm shorter than it should be. So we had to extend it by scarfing. So we have to wait till tomorrow to put these skegs on.
There is another mistake in the stem cabin. We used the wrong nail (steel nail will go rust easily when it touches salt water. Copper, bronze or stainless nails should be used ) to fix it to the stem and did not use the block between the nail and the stem cabin (this makes it difficult to take the nail out. Fortunately Chris promised to take his tool tomorrow and help us to fix the problem).
The center skeg is also cut. James showed us how to draw the curve of the bottom on a piece of wood. And then we transfer the curve to the wood block and got the center skeg cut.
Chris (tutor) also explained the difference between lamination and sawn. As the boat will face constant waves in the water (which might be very strong and cause lot of shock on the boat),the sawn stem or midship frame is not strong enough for these waves. This is because as sawn stem or midship frame, there will be long grain and short grain areas. Short grain areas are very weak and easy to break. So lamination is better choice as it produces much stronger stem and midship frame. More over, we can learn more from lamination as it. By the way, lamination is also more expensive.
The first boat flipped over today! (see the video)
Team 'Hory Dory" flipped their boat (James is the owner) over in the afternoon. This is really a big step forward, not only for the team but also for all CAT program students. As this is a milestone for our learning process.Congratulations! Team Hory Dory.
Hopefully we can flip our boat at the beginning of next week. I am looking forward lot of sanding work.
Wednesday
This morning, Chris (tutor) came to us before we started our work, and asked us to take 15 minutes to discuss and make a plan for the rest of our small craft building project. The reason for this is that with a clear plan and goals, we can work 10% more efficient. Actually the final plan is almost as the same as we discussed before: skegs and gunnels are for today, and other components are for next week.
Chris (tutor) also talked details about fore deck, bulk head, thwarts and other components. Especially about the fore deck, as it is not included in the plan. It seems a real challenge as there are lot of challenging details. I will write more about the fore deck after we finish it.
Another important technique Chris taught us is how to get nails out of the wood. See the video below:
The skegs are more complicated than I expected. As we extended them yesterday by scarfing, this morning is for shaping skegs to the exact shape. The first thing to do is to draw the curve of the bottom of our boat and transfer the curve to skegs. James showed us a good method to do this. So this is not a problem. Then we plane off glue and sand skegs to make it the right shape. Then, skegs are put through big sander machine to get smooth surface and right thickness.
 |
| Skegs going through big sander |
In order to install the skegs to the boat bottom, we have to fix the location of the skeg. Measured from the center line and draw lines for the skegs. And then we drilled several pilot holes on the bottom, these holes are right position for screws and reference for the skegs. After finished these preparation, spread glue on the skeg and put it on the bottom. Then screw the skegs to bottom to fix them.
After the skegs, it is our turn to work on the gunnels. Lot of cramps are used to hold the gunnel to the strake, screws are used as well. We made screws same common spacing.
It is good that we put skegs and gunnels on today. Tomorrow, we will do the sanding and clean up and we will flip over our boat tomorrow afternoon. One big step forward! Cheers!
Sunday, October 31, 2010
Small Craft Building: Week 4
Monday
Tuesday
Our goal for today was to scarf topsides and glue them together. So we can put them on the bottom and frames tomorrow. This goal made today a combination of good day and bad day. Anyway, it is a challenging goal.
The reason why this is a bad day is quite simple: we made an big error on scarfing. We scarfed the wrong side of the plywood. Which means that we can not put two pieces together. We forgot what Chris told us: check twice, cut once. I think this is because everyone in the team put too much attention on the shape of the topside as this is our first time dealing with flattened developable surface. We ignored basic skills on scarfing: mark the scarfing side, and flip it over to check it. We did not notice the error until we started to put scarfed pieces together. This is really a bad news for the team.
Luckily, after discussion with Chris, we found that we still have enough space to fix the error: cut off the wrong scarf surface, and make a new one. The plywood is just enough for this cut off. This again proved Chris' advice: always make it bigger than the plan. this second chance is quite an encouragement. The team decided to work on the scarf and finish the gluing today. Although this made us stay in the workshop until 6 pm, but this is definitely worth it.
Another exciting thing is the sanding machine. This powerful machine speeds up the scarfing and helps to save a lot of time.
Kenny glued the transom fashion piece. It took him lot of effort and time to fix the shape of the fashion piece.
Wednesday
Today's major task it to glue two garboards (lower topsides) to the bottom and midship frame. In the morning, we cut the garboard to its shape on the bandsaw. This process includes two steps: first, we cut two boards to it approximate shape; then, we nailed two boards together and cut them to the exact shape at once.
The next step is to plane their edges to make them nice and fair. Then, we put the garboard on the temporary frame, locate a fix position by screwing a hole through the garboard and the midship frame. There are several preparation work need to be done before we start gluing: put tape on the edge of the frame to prevent to glue the frame to the garboard; spread two layers of glue (first time without powder, and second time with powder). And then, we push the garboard against to the bottom and use nails and tape to attach garboard and bottom.
There are two ways to attach garboard to the bottom. One is to use nail and the other is to use tape. We decided to use the combination of these two method. On one hand, we can get less nail holes than simply using nails; on the other hand, as we are not confident (giving consideration that this is our first boatbuilding experience, we think nails, as a more conservative way to fasten the garboard to the bottom, is safer). After fastened two garboards to the bottom, we also glued the out edge between them.
Chris (tutor) also showed us an efficient way to fasten garboard to the bottom. Use a wood block, and put it between the garboard and bottom, screw through the garboard from outside to the wood block. So the block and the screw play roles like a cramp which helps to push the garboard and bottom together.
This is not the last working day of this week, as we decided to continue our work tomorrow.
Thursday
Got to the workshop at 10:10 am and started today's work with beveling the garboard. It is a little bit confusing with the bevel edge. Consulted with Chris (American) and Chris (tutor), and got several helpful advices. We used saw to cut a small gap on the garboard edge at each station (except station 0,1,2, this is because of the bevel angle of these stations, the intersects will be too high) and the transom. This gap plays as a role of the extension of the frame, and its end point is the intersect of the garboard and the frame edge. Then we used a batten to draw a line through these points. The first line was too high for bevel edge and the second was little bit low, so we decided to take the middle.
After beveled the edge, we measured the size of the strake (the upper topside), and lofted it on cut board. After several times of checking and arranging it on the plywood sheep, we get our strake (as the process is exactly the same as the starboard, so this time it is much easier). One thing needs to be noticed is that we are also going to cut the bulk head from the same sheet, so it took us a while to arrange the cutting plan in order to get the most out of the plywood sheet we have.
Then it is time to scarf the strake pieces. This time we double checked the scarf surface and make sure that they are the right sides that should be scarfed. We marked them and used the belt sander. Then, we planed them by hand.
After scarfing, we spread glue on scarf surface (twice, one without powder, and the second with powder). Fixed them on the table. Next Monday, we will cut them to the exact shape and attach them on the boat.
This morning, I started with beveling the stem. It took me about 40 minutes to finish the beveling and get the stem the right shape.Later, the stem was fixed to the jig and ready for the bottom.
Sebastien continued working on the midship section, while Kenny and Tian continued working on the transom.
Later in the morning, Jade and I worked on the beveled frame. Using batten and wood block to measure the bevel of the frame (for the topside of the dory).
In the afternoon, we put the bottom on the frame. Clue it to the stem and transom. We also used crump and screw to fix it to the frame and bend it to the right shape. We had a small problem with midship section as we found a gap between the midship section and the bottom. Vaughn's recommendation was to bevel the midship section's surface which was attached to the bottom.He showed us how to use 'plane' in style: quick and accurate. It only took him about 10 seconds to fix the problem and get the midship section the right shape. I did not even got a chance to make a video. Quick hand Vaughn.
It seems we are a little bit behind as there are only two weeks (8 working days) left for our dory. Tomorrow we plan to finish the topside which include 4 pieces of plank (scarf them and glue them). And we will also finish the transom fashion pieces. Hopefully we can turn the dory up next Monday and start to work on the inside.
Tuesday
Our goal for today was to scarf topsides and glue them together. So we can put them on the bottom and frames tomorrow. This goal made today a combination of good day and bad day. Anyway, it is a challenging goal.
The reason why this is a bad day is quite simple: we made an big error on scarfing. We scarfed the wrong side of the plywood. Which means that we can not put two pieces together. We forgot what Chris told us: check twice, cut once. I think this is because everyone in the team put too much attention on the shape of the topside as this is our first time dealing with flattened developable surface. We ignored basic skills on scarfing: mark the scarfing side, and flip it over to check it. We did not notice the error until we started to put scarfed pieces together. This is really a bad news for the team.
Luckily, after discussion with Chris, we found that we still have enough space to fix the error: cut off the wrong scarf surface, and make a new one. The plywood is just enough for this cut off. This again proved Chris' advice: always make it bigger than the plan. this second chance is quite an encouragement. The team decided to work on the scarf and finish the gluing today. Although this made us stay in the workshop until 6 pm, but this is definitely worth it.
Another exciting thing is the sanding machine. This powerful machine speeds up the scarfing and helps to save a lot of time.
Kenny glued the transom fashion piece. It took him lot of effort and time to fix the shape of the fashion piece.
Wednesday
Today's major task it to glue two garboards (lower topsides) to the bottom and midship frame. In the morning, we cut the garboard to its shape on the bandsaw. This process includes two steps: first, we cut two boards to it approximate shape; then, we nailed two boards together and cut them to the exact shape at once.
The next step is to plane their edges to make them nice and fair. Then, we put the garboard on the temporary frame, locate a fix position by screwing a hole through the garboard and the midship frame. There are several preparation work need to be done before we start gluing: put tape on the edge of the frame to prevent to glue the frame to the garboard; spread two layers of glue (first time without powder, and second time with powder). And then, we push the garboard against to the bottom and use nails and tape to attach garboard and bottom.
There are two ways to attach garboard to the bottom. One is to use nail and the other is to use tape. We decided to use the combination of these two method. On one hand, we can get less nail holes than simply using nails; on the other hand, as we are not confident (giving consideration that this is our first boatbuilding experience, we think nails, as a more conservative way to fasten the garboard to the bottom, is safer). After fastened two garboards to the bottom, we also glued the out edge between them.
Chris (tutor) also showed us an efficient way to fasten garboard to the bottom. Use a wood block, and put it between the garboard and bottom, screw through the garboard from outside to the wood block. So the block and the screw play roles like a cramp which helps to push the garboard and bottom together.
This is not the last working day of this week, as we decided to continue our work tomorrow.
Thursday
Got to the workshop at 10:10 am and started today's work with beveling the garboard. It is a little bit confusing with the bevel edge. Consulted with Chris (American) and Chris (tutor), and got several helpful advices. We used saw to cut a small gap on the garboard edge at each station (except station 0,1,2, this is because of the bevel angle of these stations, the intersects will be too high) and the transom. This gap plays as a role of the extension of the frame, and its end point is the intersect of the garboard and the frame edge. Then we used a batten to draw a line through these points. The first line was too high for bevel edge and the second was little bit low, so we decided to take the middle.
After beveled the edge, we measured the size of the strake (the upper topside), and lofted it on cut board. After several times of checking and arranging it on the plywood sheep, we get our strake (as the process is exactly the same as the starboard, so this time it is much easier). One thing needs to be noticed is that we are also going to cut the bulk head from the same sheet, so it took us a while to arrange the cutting plan in order to get the most out of the plywood sheet we have.
Then it is time to scarf the strake pieces. This time we double checked the scarf surface and make sure that they are the right sides that should be scarfed. We marked them and used the belt sander. Then, we planed them by hand.
After scarfing, we spread glue on scarf surface (twice, one without powder, and the second with powder). Fixed them on the table. Next Monday, we will cut them to the exact shape and attach them on the boat.
Thursday, October 28, 2010
Great! use Blog This (an free extension for Google Chrome) to move my blogs to blogger from typepad
Moving from typepad to blogger is a good idea for our course blog, but one thing that really annoying is that there seems no way to move our old blogs directly from typepad. I found a good way, at least for Google Chrome browser. Download the free extension Blog This! (link: https://chrome.google.com/extensions/detail/pengoopmcjnbflcjbmoeodbmoflcgjlk), install it to your Chrome. Then open your post in typepad, copy all the contents (including text and pictures). Then click 'blog this' button on your chrome (this will open a new window which is exact the blogger style posting window), past all the content to the new opened window. Click 'publish'. And then, everything is done. Your old post is now posted on your blogger blog, including pictures!
One deficiency is that you can not label the post in Blog This! you have to edit it back to your blogger blog.
Notice, Blog This! is only for Chrome. Have no idea if there is other versions for IE or other explorer/browser.
One deficiency is that you can not label the post in Blog This! you have to edit it back to your blogger blog.
Notice, Blog This! is only for Chrome. Have no idea if there is other versions for IE or other explorer/browser.
10/08/2010 Decoding the Boat Plan - Wei Shi's blog
10/08/2010 Decoding the Boat Plan - Wei Shi's blog
This morning , we started with discussing those joints we made yesterday. We discussed essential skills for making a joint, including cutting, dressing (D4S, D2S), ratio (1:6, 1:8), sawing, chiseling, sketching, etc.. We still have lot of work to do to improve our skills. Chris also pointed out that in order to get the job done, marking out is an important step between the start and the finish.
After this review, Chris started to give us introduction of lofting. Today's topic is the decoding the boat plan. The table of offsets (which tells the location of important intersects in the lines plan) and Simpson's 1/3 rule (which is used to calculate the displacement of the boat) were introduced and explained by Chris. He also explained the link between the table of offsets and the lines plan.
Later in the afternoon, Chris went one step further to show us how to decoding the lines plan into digital by using AutoCAD to create a table which tells locations and ordinates of cheer and buttocks. We are going to continue this tomorrow.
PS: the toolbox and oilstone box are all finished now, I am going to review these two works (including the process, finishing, skills an tools etc. later this week)
12/08/2010 decoding the dinghy plan - Wei Shi's blog
12/08/2010 decoding the dinghy plan - Wei Shi's blog
Yesterday was the last day of this week for the course. Our mission was to decoding a dinghy plan and interpret it to a table which includes profile offsets and half breadth offsets for the frame of the dinghy. AutoCAD was the software we used.
The first problem is that the table of offsets we found on the student drive did not match the dinghy plan. There were six stations (plus one half station) in the plan, but only five in the table. There were other differences between the plan and the table as well, including number of buttocks and waterlines. So before we started to measure the offsets, we need to create a new table according to the plan.
After we made the correct table, we started to measure offsets. There were lot of offsets needs to be measured, so if you keep them on the screen, it will look like a mess. And you can not recognized those measurements yourself when you want to check them later. There are two ways to keep your screen clean: the first is to delete your measurements after you fill them in the table; the second is to create several new layers in AutoCAD for your offsets, for example, you can create a new layer for your offsets for sheer, then another new layer for canoe body, then you can just hide them when you done the measurement. Of course I used the second way. It is easy for me to check my measurement later and to keep the screen clean.
The second problem was the chine in the half breadth. When you zoom in to the chine, you can find there are two chines. There should be only one. The reason for this is that because Chris drew the plan in Autoship, and the program defined the topside and the bottom side of the dinghy. When Chris faired the dinghy, Autoship calculated the topside and the bottom side separately, and then we got a gap between the topside and the bottom side. This is not a big problem, as the gap is quite tiny. But it is quite confusing when we saw this gap first time. The solution is pick your chine for your measurement, and delete another one.
Review of Oilstone Box - Wei Shi's blog
Review of Oilstone Box - Wei Shi's blog:
right size for the inset: make it a little bigger than the oilstone. After all, the biggest problem is not that you can not put your oilstone in, the biggest problem is that you can not get your oilstone out (if the inset is just the size of the oilstone, the stone may get stuck and difficult to get it out)
After finishing the inset, plane was used to make bevel of the top of the box. This was my first time using plane to make the bevel. Thanks for Chris and Vaughn for showing me how the use the plane.
The final step is to make the hollow at the bottom. This is even harder than the inset. I used bandsaw, chisel and spike shaver and finally I got the shape of the hollow.
This is my finished oilstone:
AutoCAD Assignment - Wei Shi's blog
AutoCAD Assignment - Wei Shi's blog:
"AutoCAD Assignment
Yesterday we did an AutoCAD�assignment. We were asked to draw centerboard and rudder according to an existing plan in AutoCAD. Our drawing should include several different layers for lines, dim, text and we need to make new layout in paper space to display our drawing in right scale.�
The assignment included five stages:�
1.Sketch. We need to sketch the plan on paper, copy necessary information from the original plan. I think this is the most important part. The sketch will tell you what to draw. It provides basic information for the assignment.
2. Drawing in AutoCAD. Follow instructions of the assignment, create different layers, create drawing from the sketch.
3. Print out draft.�
4. Mark out. Check your draft with Chris, and to see if there is any mistakes. Mark them out, and then go back to your computer and fix them in AutoCAD.
5. Print the final drawing.
At 4 pm, we handed in our marked out draft and the final drawing to Chris."
Yesterday we did an AutoCAD�assignment. We were asked to draw centerboard and rudder according to an existing plan in AutoCAD. Our drawing should include several different layers for lines, dim, text and we need to make new layout in paper space to display our drawing in right scale.�
The assignment included five stages:�
1.Sketch. We need to sketch the plan on paper, copy necessary information from the original plan. I think this is the most important part. The sketch will tell you what to draw. It provides basic information for the assignment.
2. Drawing in AutoCAD. Follow instructions of the assignment, create different layers, create drawing from the sketch.
3. Print out draft.�
4. Mark out. Check your draft with Chris, and to see if there is any mistakes. Mark them out, and then go back to your computer and fix them in AutoCAD.
5. Print the final drawing.
At 4 pm, we handed in our marked out draft and the final drawing to Chris."
AutoCAD, boat plan and faying surface - Wei Shi's blog
AutoCAD, boat plan and faying surface - Wei Shi's blog
Luckily, the course of boatbuilding is the exact process for our learning of boatbuilding knowledge. Chris showed us this morning the relationship between the faying surface and the PT (Plank Thickness).Actually, this is one of those difficulties we had in yesterday drawing. The length of the faying surface is PTx4.This is one of those important rules for boatbuilders.
This morning, we started with a discussion of our feelings of drawing a plan in AutoCAD. The small boat was designed for beginner boatbuilders, so as the plan itself.We got six sheets of plans. And guess what, everyone seems confused, because we can not decode the plan.As we were asked to draw the plan in AutoCAD, we found it is so difficult to duplicate it because we can not find enough measurements!
This proved a fact: for a boatbuilder, knowing how to use AutoCAD is far from enough. AutoCAD is powerful and useful tool, but you need to combine boatbuilding knowledge with your AutoCAD skill in order to get expected outcome (we have done several drawings in AutoCAD: tool box, oilstone box, stem section, deck camber, scupper hole...I think everyone in the team now knows how to use AutoCAD and has got basic drawing skills). That is why programmes such as AutoCAD are only computer-AIDED design programme.Luckily, the course of boatbuilding is the exact process for our learning of boatbuilding knowledge. Chris showed us this morning the relationship between the faying surface and the PT (Plank Thickness).Actually, this is one of those difficulties we had in yesterday drawing. The length of the faying surface is PTx4.This is one of those important rules for boatbuilders.
30/08/2010, Monday, Drawing - Wei Shi's blog
30/08/2010, Monday, Drawing - Wei Shi's blog
This afternoon, we started to draw a lines plan, with drawing kits in the drawing room.
Drawing a lines plan of boat is similar to lofting, the difference is the scale. When lofting, we need to loft the boat in full size. But drawing, we do it in scale of 1:10. Actually, this can explain why we need to loft the boat before we start to build it. In the drawing, because of the scale, some errors can not be seen because they are so small on the paper. However, once you loft it, you may find that the error could be something like 1cm or 10cm. This is enough to cause a lot of trouble by making lines unfair.
The step is also similar. Starts with straight line to construct the grid, then the curves.
Battens are used to draw curves, while ducks are used to hold the batten.
Lofting blog 4: Angled transom - Wei Shi's blog
Lofting blog 4: Angled transom - Wei Shi's blog
Lofting angled transom includes two parts: the first is to draw the angled transom in profile and half breadth, the second is to loft the transom on a separate card board.
In order to draw the angled transom in profile, we need a trammel arm. As in the case of this dinghy, the transom is angled 10 degree. So, just use the trammel arm to draw an arc (use the intersect of AP and sheer as the center for the arc). Pick the point on the arc which is 100 mm from the intersect of AP and the arc. Draw a line through the arc center (intersect of AP and Sheer) and this point. Then you get the angled transom in profile.
To draw the angled transom in half breadth, you need to use a sticker to measure the distance between all the lines (sheer, waterlines, buttocks, chine and canoe body) and the AP. Then, you use the sticker to transfer these data to the half breadth. With all these points, you can get the transom in half breadth.
After finish the angled transom in profile and half breadth. We can start to loft the transom on a separate piece of card board. This is the real tricky part. The center line on this card board should be paralleled to the transom in profile, which means that the center line should have an angle of 10 degree. Then draw buttocks and water lines. Then you get the grid. Use the sticker to measure width of lines (sheer, waterlines, chine) in half breadth and transfer the data to the lofting of angled transom.
Notice that transom thickness (TT) is 27mm. So we need to offset the angled transom in profile with distance of 27 mm. Use this new line to develop angled transom in half breadth and the lofting of transom.
Have to say that this angled transom is really a challenge. Drawing the transom in profile is easy, drawing it in the half breadth is ok (just be careful with the sticker and measurements), but lofting it is not easy. I had some errors on lofting the transom, but I can not figure out what was going wrong. Thanks Sebastien and Tian for his help. Sebastien helped me to find out that my horizontal lines are not perpendicular to the center line. And help me to mark the measurements and doubled checked the lofting for me. Tian helped to rubber out wrong lines and checked marks and measurements. (see pictures below)
Lofting Blog 3: Stem - Wei Shi's blog
Lofting Blog 3: Stem - Wei Shi's blog
Stem face
Stem face is a crucial part of the lofting. If you just using existing intersects, it will be hard to get the right curve. Because the stem face needs more details. The solution is to go back to the CAD lab, using CAD to drawing several ghost lines to construct a new grid (with higher density of grid lines) for the stem face, and measure those intersects of the stem face and ghost lines, then you get your stem details. Once you figure out how to do this, stem face is an easy task.
Stem section (Wednesday, 25/08/2010)
After finish the body plan, I started to draw the stem section after lunch yesterday (Tuesday). Thanks Chris for his detailed explanation for how to draw the stem section. Once you figured out how to do this, it is not a hard task. Especially with a sticker (which has markings for moulding, 1/2 siding, PT), you can draw stem sections quickly. Following are steps:
-Go to the stem face and pick a point on the curve (point X), draw a perpendicular line (line A) to point X (you can make a guess by imaging the tangent line to the curve at point X).
- Start from the intersect of line A and the butt 50, draw a ghost line (line B) which is perpendicular to line A, with length of 50. Use the point X and the endpoint of ghost line (line B) to draw line C.
- As the PT (planking thickness is 4 mm, we need to offset line C (offset distance: 4mm) to get line D
- From the start point of line D, draw the moulding (32 mm), and get the faying surface.Then from the endpoint of molding, draw the 1/2 siding (15 mm). From the endpoint of siding, draw a perpendicular line to line D. Notice the round corner at the intersect of the mold and the siding.
- Add some shading.
Picture below: finished stem sections and the sticker with markings for moulding, 1/2 siding and pt (the sticker is made by Chris)
Lofting Blog 2: Lines - Wei Shi's blog
Lofting Blog 2: Lines - Wei Shi's blog
Grid:
Before we start to draw curves, we need to construct grid. The grid consists of several straight lines, including FP, AP, Stations, Waterlines in the profile and Buttocks in the half breadth. LWL is the first line to be drawn, then the CL, the the FP. When it comes to stations, trammel arms are used to draw these perpendicular lines. We first drew one station of every three, then we can use these stations as reference to construct the rest and to check whether our measurements and drawings are correct.
After finish the grid, it is time to draw those curves. The standard process is:
1. Measure the intersects of the curve and stations in profile according to the table of offsets, and mark them out.
2. Find a good batten, and use nails to bend it to the right curve (in this case, it will be the sheer). Then use nails to fix the batten
3. Draw the curve.
4. Pull nails out, and put away the batten.
Sheer in profile:
Sheer comes after the grid according to the lofting schedule. So it will be the first curve to be drawn on the cut board. Sheer is not a tricky curve, so just follow the standard process.
Deck line in half breadth:
Deck line in half breadth is the same line called sheer in profile. Just follow the standard process. But I had a problem when I was drawing this line: the segment between FP and station 0 is not fair. It should not be. I checked my measurements, saw other guys got a beautiful curve for the their deck line using the same measurements and methods. That was really annoying. I tried several times, but failed to fix the error. The batten just tells me that this is wrong. I even started to doubt that may be my grid is wrong, that will be a disaster. Finally I got it. The deck line starts from the CL, but I made a mistake and my deck line starts from butt 50. This explains why I can not get it fair. When you are marking intersects, make sure you measure them from the right line (LWL in profile and CL in half breadth).
Chine in profile and Canoe body in profile:
Just follow the standard process, and with all the experience and skills I got from first two curves, these two curves seemed much easier.
Chine in half breadth:
Buttocks in profile:
I started to draw butt 400 in profile after finished the Chine in half breadth. Use the same technique and follow the standard process. One thing needs to be put special attention is the start of the butt 400. It is the intersect of butt 400 and the cheer. The coordination of this intersect can not be found in the table of offsets, but in the half breadth, you can find it. All you need to do is to draw a perpendicular line from the intersect of butt 400 and deck line in half breadth. The intersect of this perpendicular line and the cheer in profile, is the start of the butt 400. (see picture below)
The second crucial part of butt 400 is that this curve has a kink between station 6 and station 5. It starts at the intersect where the but 400 came across Chine. But I did not notice this (actually, I have no idea about this), so I just used the batten to draw a curve. Chris saw that and made a laugh at me (well, I am not the only one who had been laughed by Chris for this mistake, almost everyone made this mistake). Ben explained this to us by showing us a real dinghy in the workshop. So what should I do? Erase the segment of the kink, measure the kink in AutoCAD, and draw it again.
There is a kink at the front part of the butt 400 (it is located at the intersect of butt 400 and chine) as well. From the kink to the intersect of the butt 400 and the Cheer, it is not a curve, but a segment which consists of three straight lines.
Body plan (Monday, 23/08/2010)
This is the second week of our lofting training. I continued to draw waterlines in half breadth and buttocks in profile. I would say it went quite smooth despite some minor problems. The profile and half breadth were finished before lunch time.
I started the body plan after lunch.Thanks for Eran and Vaughn showed me the technique for body plan. There is no need for measurement of those intersects as we can get all the information from the profile and the half breadth which are already done. The technique is not complicated, or once you understand it, you would say it is quite easy. But it may take you days to figure out how to do this without introductions or explanations from an expert. Boatbuilding knowledge, experience and skills that handed down from generation to generation are high valued assets.
The first to do is to construct the grid for the body plan. With center line in the middle, butt 50, butt 200 and butt 400 on both sides of the center line. Waterlines are the same as those in profile.
The method to draw the body plan is to use a paper tape. At every station, you mark the height of every intersect in profile on one side of the paper tape and the width of every intersect in half breadth on the other side of the paper tape. Then you can just use these marks to locate these intersects in the body plan. After you draw these intersects, use batten to draw lines in body plan.
I finished several lines in body plan today, and still have four lines to go. I will finish them tomorrow.
Some guys have already finished body plan. James was the first (see picture below: James and his finished work). Good job!
Lines are finished on 25/08/2010. :) Picture below: finished body plan
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